Endocrine System: Histology Oms 6120

Front 1

Direct communication

Back 1

cell - cell cross-talk occurs through channels (gap junctions) connecting directly adjacent cells

Front 2

Paracrine communication

Back 2

cells secrete factors/hormones that act locally.

Front 3

Endocrine communication

Back 3

cells secrete hormones that enter the bloodstream and are carried to distant target sites.

Front 4

Synaptic communication

Back 4

cells (neurons here) secrete neurotransmitter molecules that act upon immediately adjacent receptor sites.

Front 5

Hypothalmus Hormones

Back 5

ADH, oxytocin, and regulatory hormones

Front 6

Pituitary Gland Hormones

Back 6

Anterior lobe: ACTH, TSH, GH, PRL, FSH, LH, MSH

Posterior Lobe: Storage and release of oxytocin and ADH

Front 7

Thyroid Gland Hormones

Back 7

Thyroxine (T4), Triiodothyronine (T3), Calcitonin (CT)

Front 8

Thymus Hormones

Back 8

thymosins
undergoes atrophy during adulthood

Front 9

Suprarenal Gland Hormones

Back 9

Medulla: Epinephrine, Norepinephrine

Cortex: cortisol, corticosterone, aldosterone, androgens

Front 10

Pineal Gland Hormones

Back 10

Melatonin

Front 11

Parathyroid Gland Hormones

Back 11

Parathyroid Hormone (PTH)

Front 12

Heart Hormones

Back 12

atrial natriuretic peptide (ANP)
brain natriuretic peptide (BNP)

Front 13

Kidney Hormones

Back 13

Erythropoietin (EPO), calcitriol

Front 14

Adipose Tissue Hormones

Back 14

Leptin

Front 15

Digestive Tract Hormones

Back 15

numerous hormones

Front 16

Pancreatic Islet Hormones

Back 16

Insulin, glucagon

Front 17

Testes Hormones

Back 17

androgens (testosterone), inhibin

Front 18

Ovary Hormones

Back 18

estrogens, progestins, inhibin

Front 19

Three molecular types of hormones

Back 19

1. Amino acid derivatives.
2. Peptide hormones.
3. Lipid derivatives: steroids and eicosanoids

Front 20

Steroid Hormones

Back 20

cholesterol-derived hormones synthesized and secreted by cells of the ovaries, testes, and adrenal cortex.(gonadal and adrenocortical steroids)
released into the bloodstream and transported to target cells with the help of plasma proteins or specialized carrier proteins that protect the hormone from degradation during transport to the target tissue.

Front 21

Small Peptides, Polypeptides, and Protein Hormones

Back 21

synthesized and secreted by cells of the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, pancreas, and scattered enteroendocrine cells of the gastrointestinal tract and respiratory system.
(e.g., insulin, glucagon, GH, ACTH, FSH, LH, ADH, oxytocin, interleukins, various growth factors)
generally do not require special transport proteins.
most if not all polypeptides and proteins have specific carrier proteins (e.g., insulin growth factor-binding protein or IGFBP).

Front 22

Amino Acid Hormones

Back 22

arachidonic acid analogs and derivatives, including the catecholamines (norepinephrine and epinephrine-phenylalanine/tyrosine derivatives) and prostaglandins, prostacyclins, and leukotrienes (arachidonic acid derivatives).
synthesized and secreted by many neurons as well as a variety of cells including cells of the adrenal medulla.
thyroid hormones
When released into the circulation, catecholamines dissolve readily in the blood, in contrast to thyroid hormones that bind to the prealbumin fraction of serum proteins (transthyretin) and a specialized thyroxin-binding protein.

Front 23

Amino Acid Hormone Structure

Back 23

small molecules structurally related to individual amino acids

Front 24

Peptide Hormone Structure

Back 24

chains of amino acids

Front 25

Lipid Derivative Hormone Structure

Back 25

carbon rings and side chains built from fatty acids or cholesterol

Front 26

Eicosanoids

Back 26

lipid derivatives of arachidonic acid

eg: leukotrienes, prostaglandins, thromboxanes, prostacyclins

Front 27

Down-regulation

Back 27

the presence of the appropriate hormone results in a reduction of receptor numbers. A common result. Remember: homeostasis must be preserved

Front 28

Up-regulation

Back 28

the absence of a hormone triggers an increase in receptor numbers.
Here, a cell would become more sensitive to a low level of circulating hormone - again an attempt to maintain homeostasis.

Front 29

G Proteins

Back 29

a plasma membrane bound enzyme complex that bind GTP. They are activated when the appropriate hormone binds to its plasma membrane receptor.
intermediary molecule btwn first and second messengers

Front 30

humoral stimuli

Back 30

content of the extracellular fluid changes

Front 31

hormonal stimuli

Back 31

The “right” hormone arrives on the scene

Front 32

neural stimuli

Back 32

neurotransmitters show up at the correct sites

Front 33

Simple Endocrine Reflexes

Back 33

Only one hormone involved.

Endocrine cells respond directly to changes in the surrounding extracellular fluid.

Homeostasis is adjusted as required.

A major method of regulating the heart, pancreas, parathyroid glands and the digestive tract.

Front 34

Complex Endocrine Reflexes

Back 34

These involve two or more hormones

examples are the interactive relationships between the hypothalamus and the rest of the endocrine system.
1. Releasing factors affect the anterior pituitary.
2. Neurohypophysis secretes ADH and oxytocin.
3. Direct control over the suprarenal medulla.

Front 35

Pituitary gland functional components:

Back 35

• Anterior lobe (adenohypophysis), the glandular epithelial tissue

• Posterior lobe (neurohypophysis), the neural secretory tissue

Front 36

Pars Distalis Hormones

Back 36

TSH, ACTH, FSH, LH, GH, Prolactin

Front 37

Pars Intermedia Hormones

Back 37

MSH

Front 38

Pars Nervosa Hormones

Back 38

ADH, Oxytocin

Front 39

Pituicytes

Back 39

Supporting cells of the posterior pituitary

These do NOT synthesize or secrete hormones.

Front 40

Oxytocin and ADH (vasopressin) stored in....

Back 40

Pars Nervosa (Posterior Pituitary; Herring Bodies)

Front 41

Oxytocin/ADH synthesized in....

Back 41

the neuronal cell bodies located in the hypothalamus

Front 42

Oxytocin/ADH transported to the pars nervous via....

Back 42

the hypothalamal-hypophysial tract (axons)

Front 43

Pinealocytes

Back 43

the chief cells of the pineal gland arranged in clumps or cords within lobules formed by connective tissue septa that extend into the gland from the pia mater that covers its surface.

have a large, deeply infolded nucleus with one or more prominent nucleoli and contain lipid droplets within their cytoplasm.

Front 44

corpora arenacea

Back 44

brain sand
calcified concretions in the pineal gland

Front 45

Herring Bodies

Back 45

dilations formed from aggregations of neurosecretory vesicles in the pars nervosa

contain either ADH or oxytocin

Front 46

Principal (chief) cells

Back 46

the more numerous of the parenchymal cells of the parathyroid, are responsible for the secretion of PTH.
small, polygonal cells, with a centrally located nucleus

Front 47

Oxyphil cells

Back 47

a minor portion of the parenchymal cells of the parathyroid
not known to have a secretory role.

found singly or in clusters; the cells are more rounded, considerably larger than the principal cells, and have a distinctly acidophilic cytoplasm

Front 48

Parathyroid hormone (PTH) acts to...

Back 48

increase Ca+2 in body fluids. PTH is made and secreted by the parathyroid cells

Front 49

Calcitonin acts to...

Back 49

decrease Ca+2 in body fluids; opposes PTH

produced in the Thyroid gland

Front 50

Adrenal cortex

Back 50

the steroid-secreting portion.

lies beneath the capsule and constitutes nearly 90% of the gland by weight.

Front 51

Adrenal medulla

Back 51

the catecholamine-secreting portion.

lies deep to the cortex and forms the center of the gland.

Front 52

Zona glomerulosa

Back 52

the narrow outer zone of the adrenal cortex

A rich network of fenestrated sinusoidal capillaries surrounds each cluster of ovoid cells

secretes mineralocorticoids (aldosterone), which functions in the control of blood pressure

Front 53

Zona fasciculata

Back 53

the thick middle zone of the adrenal cortex

cells are large and polyhedral, arranged in long straight cords, one or two cells thick, that are separated by sinusoidal capillaries

secretes glucocorticoids that regulate glucose and fatty acid metabolism

Front 54

Zona reticularis

Back 54

the inner zone of the adrenal cortex

cells are noticeably smaller than those of the zona fasciculata, and nuclei are more deeply stained. cells arranged in anastomosing cords separated by fenestrated capillaries

principal secretions are weak androgens

Front 55

Hormones of the Adrenal Medulla

Back 55

Epinephrine, Norepineprhine

Front 56

Alpha Cell Secretions

Back 56

Glucagon

Front 57

Beta Cell Secretion

Back 57

Insulin

Front 58

Gamma/Delta Cell Secretion

Back 58

Somatostatin

Front 59

F Cell Secretion

Back 59

Pancreatic Polypeptide